Okay, so there were basically 2 problems with trading last time that I remember
1) A pair of GMs consistently trying to push through lopsided trades. Basically, one GM drafted Vladimir Lutchenko, got obsessed with the idea of reuniting him with his real-life partner Valeri Vasiliev, and kept trying to trade Slava Fetisov (a much better player than Vasiliev) for Vasiliev and scraps.
Possible solution: 3 strikes and you're out. If you have 3 vetoed trades, you can't trade for the rest of that ATD. Period. Considering that last ATD was the first time that we even reached 3 vetoed trades between every GM combined, I don't think this will put an unfair burden on anyone.
2) GMs making controversial megatrades multiple times right before their turn, which held up the draft.
Hypothetical example:
A hypothetical GM (we'll just call him "LeafsAlways") has pick 82. The draft is now on pick 80. He makes a controversial megatrade that trades away pick 82 and it holds up the draft as we wait for it to be reviewed. Both GMs say no picks until they know if the trade is approved. Finally the trade goes through. Right after pick 82 is made (by the guy who traded for it), LeafsAlways makes another controversial megatrade to trade up, this time for pick 84. Again, the draft is held up.
The result: LeafsAlways traded from pick 82 to pick 84 (with a lot of later picks exchanged) and the draft got held up twice, once for each trade that resulted in him moving back 2 spots in the end.
Tougher to think of a solution for this one, but I have a few ideas:
a) Cap the number of trades but make it really high. An 8 trade maximum shouldn't affect most GMs but would put a damper on megatrades that serve no real purpose other than for the sake of trading.
b) This is something that I've thought should happen for a long time, but never gets much support. No more than 4 picks/player per side in a trade. Trades involving 2 or 3 picks are easy to evaluate. Trades involving 4 picks are tougher but not crazy tough. Trades involving 5 picks going to each way often have to be discussed. The vast majority of controversial trades in ATDs are these megatrades with 5 or more picks going each way, and maybe it's time to get rid of them.
A softer version of this rule: If you want to trade 5 or more picks/players at once, you must complete the trade and submit it to the trade committee at least 1 full round before the first pick of the trade is to be selected. (Or for trades involving 1st round picks, you need to complete it before the clock officially starts running for anyone).